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Image forming apparatus

Inactive Publication Date: 2016-09-08
CANON KK
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides an image forming apparatus that can form a high-quality toner image on a transfer receiving member with minimal toner waste. This is achieved by detecting information on the voltage and current when the voltage is applied to the transfer member, and adjusting the potential difference between the photosensitive member and the developing voltage so as to be large when the transfer voltage set by the setting portion is a first threshold or more and the current flowing at the time of application of the transfer voltage to the transfer member is a second threshold or less.

Problems solved by technology

However, in the image forming apparatus employing the DC charging type and the pre-exposure-less type, it turned out that a phenomenon of “positive ghost” is liable to generate.
However, in some cases, the transfer current cannot be sufficiently increased depending on deterioration due to use of the transfer member and an environment of use (operation).
In such a case, the image forming apparatus employing the DC charging type and the pre-exposure-less type is disadvantageous in terms of t positive ghost for the following reason.
That is, in the AC / DC charging type, by the potential smoothing effect of the AC voltage, potential non-uniformity of the photosensitive member is smoothened (eliminated) when the photosensitive member is electrically charged and thus the photosensitive member charge potential is easily uniformized, and therefore the positive ghost does not readily generate.
However, in the DC charging type, for such a reason that the potential smoothing effect of the AC voltage cannot be obtained, the DC charging type is disadvantageous against the positive ghost when compared with the AC / DC charging type.
Further, the pre-exposure device removes the potential on the photosensitive member after the transfer step and before a charging step and can uniformly cancel the photosensitive member surface potential before the charging step, and therefore the positive ghost does not readily generate.
However, in the DC charging type, for such a reason that such a photosensitive member surface potential canceling effect cannot be obtained, the DC charging type is disadvantageous against the positive ghost when compared with the AC / DC charging type.

Method used

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Experimental program
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embodiment 1

1. General Structure and Operation of Image Forming Apparatus

[0024]FIG. 1 is a schematic sectional view showing a general structure of an image forming apparatus 100 in this embodiment according to the present invention.

[0025]The image forming apparatus 100 in this embodiment is a tandem-type printer which is capable of forming a full-color image using an electrophotographic type and which employs an intermediary transfer type.

[0026]The image forming apparatus 100 includes four image forming portions (stations) SY, SM, SC and SK which are arranged in a line with regular intervals and which form images of yellow (Y), magenta (M), cyan (C) and black (K), respectively.

[0027]Incidentally, in this embodiment, constituting and operations of the image forming portions SY, SM, SC, SK are substantially the same except that colors of toners used in a developing step are different from each other. Accordingly, in the following, in the case where particularly distinction is not required, suffix...

embodiment 2

[0090]Another embodiment of the present invention will be described. Basic constitution and operation of an image forming apparatus in this embodiment are the same as those in Embodiment 1. Accordingly, elements having the same or corresponding functions and constitutions as those for the image forming apparatus in Embodiment 1 are represented by the same reference numerals or symbols, and will be omitted from detailed description.

[0091]In Embodiment 1, whether or not the VD offset should be executed was discriminated depending on whether or not a result of detection, by the current detecting circuit 121, of the transfer current value when the primary transfer bias having the transfer voltage volume determined in the PTVC is not more than the second threshold. On the other hand, in this embodiment, the detection, by the current detecting circuit 121, of the transfer current value when the primary transfer bias having the transfer voltage volume determined in the PTVC is not made. In...

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Abstract

An image forming apparatus includes a photosensitive member, a charging member, a charging voltage source, an exposure device, a developing device, a developing voltage source, a transfer member, a transfer voltage source, a detecting member, a setting portion for setting, a transfer voltage applied to the transfer member on the basis of a detection result of the detecting member, and an adjusting portion for increasing a potential difference between the potential of the photosensitive member charged and the developing voltage so as to be large when an absolute value of the transfer voltage set by the setting portion is a first threshold or more and an absolute value of the current flowing at the time of application of the transfer voltage to the transfer member is a second threshold or less.

Description

FIELD OF THE INVENTION AND RELATED ART[0001]The present invention relates to an image forming apparatus, such as a copying machine, a printer or a facsimile machine, using an electrophotographic type or an electrostatic recording type.[0002]Conventionally, in an electrophotographic image forming apparatus, there are techniques such as a DC charging type and a pre-exposure-less type.[0003]The DC charging type is the following technique. As a means for an electrophotographic photosensitive member, there is a type in which electroconductive charging member is brought in contact with or near o the photosensitive member and a voltage is applied to the charging member to perform a charging process (hereinafter referred to as a “contact charging type”). The charging process of the photosensitive member by the charging member is performed by electric discharge in a minute gap (spacing) between the charging member and the photosensitive member, and therefore to the charging member, a voltage...

Claims

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Application Information

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IPC IPC(8): G03G15/00G03G15/16G03G15/06G03G15/02
CPCG03G15/0266G03G15/0189G03G15/065G03G15/1675G03G15/5037
Inventor MATSUURA, TAISUKE
Owner CANON KK